In recent years, due to the increase of costs associated with producing electricity from fossil fuels, renewable energy technology has gained interest. In particular, among the plurality of renewable energy technologies, Concentrated Photovoltaic (CPV) technology has been the subject of much research. The advantage of CPV over the non-concentrated photovoltaic technology results from the fact that CPV can produce the same amount of electricity of a much larger non-concentrated photovoltaic cell by focusing the sunlight via a lens on a smaller active semiconductor area. In particular, Fresnel lenses are used for CPV technology. As a result of this approach, it is possible to reduce the costs associated with the manufacturing of the photovoltaic cell since the materials used are reduced.
However, by concentrating the sunlight in such a manner, CPV systems have a tendency to increase their temperature during operation. This negatively affects the efficiency of the photovoltaic conversion. Accordingly, it is often necessary to position CPV cells on top of structures capable of removing excessive heat from the cells, such as passive or active heat sinks.
The CPV cell is, therefore, usually assembled on top of a heat sink, which is thereafter assembled on top of a base plate of a solar module. The module is then further completed by the lenses concentrating sunlight on the CPV cells. Such arrangement requires a plurality of steps at the assembly manufacturing plant, which may introduce a misalignment between the lens and the CPV cell, resulting in poor efficiency of the module.
In particular, as schematically illustrated in FIG. 4, a photovoltaic module 4000 comprises a base plate 4100, on top of which a plurality of heat sinks 4201 and 4202 are mounted. Each of the heat sinks has a CPV cell 4301, 4302 mounted thereon. The photovoltaic module 4000 further comprises a module structure, here schematically represented by a pillar 4400, which sustains lenses layer 4500, comprising lenses 4510 and 4520. Accordingly, when exposed to sunlight, the light is concentrated by lenses 4510 and 4520 on CPV cells 4301 and 4302, respectively. The CPV cells 4301 and 4302 transform sunlight into electricity, but also heat up while being illuminated, since they do not have an ideal 100% efficiency. The excess heat is removed by means of heat sinks 4201 and 4202, respectively.
FIG. 4A schematically illustrates a top view of photovoltaic module 4000. In particular, in FIG. 4A, four CPV cells are illustrated. However, for clarity of representation, the top two are illustrated with the lenses 4510 and 4521 in place, while lenses 4510 and 4520 for the bottom two CPV cells have been represented only by dashed lines. In a non-limitative way, lenses 4510 and 4520 are represented schematically in a rectangular shape, but can have any other suitable shape, and can be, for instance, square-shaped Fresnel lenses commonly used for CPV.
FIGS. 4 and 4A illustrate the ideal placement of CPV cells with respect to the corresponding lens, for achieving maximum efficiency of the photovoltaic module 4000. However, such ideal placement is hindered in practice by the assembling process, illustrated in FIG. 5.
As can be seen in FIG. 5, the assembling process usually starts with (i) the placement of CPV cells 4301, 4302, on top of respective heat sinks 4201, 4202, in a step S50. This is subjected to a first misalignment error, which could be, for instance, in the range of +/−10 μm. The structures so realized are then placed on the base plate 4100 via a step S51. This is subjected to a second misalignment error, which could be, for instance, in the range of +/−10 μm. During a subsequent step S52, the addition of a module structure or pillar 4400 and a lenses layer 4500 result in the placement of lenses 4510 and 4520 over the CPV cells 4301 and 4302. This is subjected to a third misalignment error. This process can, therefore, be subjected to several misalignment errors, occurring at each of the assembly steps. For instance, FIGS. 6 and 6A illustrate a photovoltaic module 6000, a case in which the CPV cell 6303 and heat sink 6203 are misaligned, with respect to their respective ideal positions 4302A and 4202A. In this case, the misalignment introduced at any of steps S50-S52 results in a final misalignment between the lens 4520 and the CPV cell 6303, thereby decreasing the efficiency of module 6000.
The above-mentioned problems are solved by the teaching of this disclosure.